URL-parameters and logic in Django class-based views (TemplateView)

Question

It is unclear to me how it is best to access URL-parameters in class-based-views in Django 1.5.

Consider the following:

View:

Answer 1

In case you pass URL parameter like this:

http://<my_url>/?order_by=created

You can access it in class based view by using self.request.GET (its not presented in self.args nor in self.kwargs):

class MyClassBasedView(ObjectList):
    ...
    def get_queryset(self):
        order_by = self.request.GET.get('order_by') or '-created'
        qs = super(MyClassBasedView, self).get_queryset()
        return qs.order_by(order_by)

Answer 2

I found this elegant solution, and for django 1.5 or higher, as pointed out here:

Django’s generic class based views now automatically include a view variable in the context. This variable points at your view object.

In your views.py:

from django.views.generic.base import TemplateView    

class Yearly(TemplateView):
    template_name = "calendars/yearly.html"
    # Not here 
    current_year = datetime.datetime.now().year
    current_month = datetime.datetime.now().month

    # dispatch is called when the class instance loads
    def dispatch(self, request, *args, **kwargs):
        self.year = kwargs.get('year', "any_default")

    # other code

    # needed to have an HttpResponse
    return super(Yearly, self).dispatch(request, *args, **kwargs)

The dispatch solution found in this question.
As the view is already passed within Template context, you don't really need to worry about it. In your template file yearly.html, it is possible to access those view attributes simply by:

{{ view.year }}
{{ view.current_year }}
{{ view.current_month }}

You can keep your urlconf as it is.

It's worth mentioning that getting information into your template’s context overwrites the get_context_data(), so it is somehow breaking the django's action bean flow.

Answer 3

How about just use Python decorators to make this intelligible:

class Yearly(TemplateView):

    @property
    def year(self):
       return self.kwargs['year']

Answer 4

So far I've only been able to access these url parameters from within the get_queryset method, although I've only tried it with a ListView not a TemplateView. I'll use the url param to create an attribute on the object instance, then use that attribute in get_context_data to populate the context:

class Yearly(TemplateView):
    template_name = "calendars/yearly.html"

    current_year = datetime.datetime.now().year
    current_month = datetime.datetime.now().month

    def get_queryset(self):
        self.year = self.kwargs['year']
        queryset = super(Yearly, self).get_queryset()
        return queryset

    def get_context_data(self, **kwargs):
        context = super(Yearly, self).get_context_data(**kwargs)
        context['current_year'] = self.current_year
        context['current_month'] = self.current_month
        context['year'] = self.year
        return context

Answer 5

To access the url parameters in class based views, use self.args or self.kwargs so you would access it by doing self.kwargs['year']